Phytoneuron

/ of Eutrochium purpureum (Eupatorieae: Asteraceae). Phytoneuron 2010-43:

A NEW VARIETY OF EUTROCHIUM PURPUREUM
(EUPATORIEAE: ASTERACEAE)

Bruce A. Sorrie

University of North Carolina Herbarium

North Carolina Botanical Garden
Chapel Hill, NC 27599-3280

ABSTRACT
Eutrochium purpureum var. carolinianum Sorrie var. nov. is described from the lower
piedmont of North Carolina and South Carolina, USA. Its morphological features are compared with
the two currently recognized varieties of E. purpureum.
KEY WORDS: Eutrochium purpureum var. carolinianum Sorrie var. nov., Asteraceae, Eupatorieae

Atypical specimens of Eutrochium purpureum (L.) E. Lamont (= Eupatorium purpureum L.)
found in the lower piedmont of North Carolina and South Carolina, represent a distinct and
previously unrecognized variety.

Eutrochium purpureum (L.) E. Lamont var. carolinianum Sorrie, var. nov. Figs. 1, 2, 3. TYPE:
USA. North Carolina. Stanly Co.: open powerline southeast of Stony Hill Church,
dominated by grasses and herbs, dry soil derived from mafic rock, common, 14 July 2009,
B.A. Sorrie 12380 (holotype: NCU).

Eutrochio purpureo vaj
acutis, omnino dense lanulosis
numerosioribus elongatioribus.

Etymology. The varietal name is derived from the two-state region in which the plants grow.
Species formerly treated within Eupatorium sect. Verticillatum DC. have recently been segregated as
the genus Eutrochium Raf (Lamont 2006).

Additonal collections examined. North Carolina. Anson Co: upland woods, Pee Dee River,
2.5 mi northeast of Old Sneedsboro, 21 Sep 1956, Ahles 19432 with Leisner (NCU). Cabarrus Co.:
low woodland border, 1.2 mi west of jet. of NC 27 and US 601 on NC 27, 23 Sep 1956, Ahles 19754
with Leisner (NCU). Gaston Co. : wooded stream, 4. 1 mi exist of Gastonia just north of US 29-74 on
Ranlo Road, 17 Sep 1956, Ahles 1S857 with Leisner (NCU). Montgomery Co.: woodland border, 1.8
mi southeast of Montgomery-Stanly county line (Pee Dee River) on NC 27-73, 6 Jul 1956, Ahles
16290 with Leisner (NCU), Moore Co.: narrow powerline on steep slope, George P Road north of
Deep River, 24 Jul 2005, Sorrie 11664 (NCU). Richmond Co.: west of US 1 and east of Pee Dee
River, along dirt logging road, disturbed loblolly pine plantation with regenerating hardwoods, 22 Jun
1999, Sorrie 10175 (NCU). Stanly Co.: upland oak woods, 1.7 mi south of Mllingport on
Mllingport-Lambert Road, 6 Jul 1956, Ahles 16213 with Leisner (NCU); north side Jacobs Creek,
southwest of SR 1739, frequent in ravine on side of high hill, 17 Oct 2007, Sorrie 12054 (NCU).
Union Co.: roadside, 0.8 mi north-northwest of Waxhaw on NC 16, 14 Jul 1957, Ahles, 31387 with
Haesloop (NCU); roadside bank on Austin Road (SR 1256), 0.4 mi north of South Carolina line, 12
Jul 2010, Sorrie 12624 (NCSC). South Carolina. Abbeville Co.: roadside, Parsons Mountain, 6 mi
south of Abbeville, 29 Jun 1957, Radford 25939 (NCU). Fairfield Co. : roadside at jet. county routes
22 and 28 west of Woodward, 26 Jun 1957. Bell 9354 (NCU). Lancaster Co.: rich mesic woods, 40
Acre Rock, NNE of Kershaw, 6 Jun 1957, Ahles 27456 with Haesloop (NCU). York Co.: wooded

Some: Eutrochium purpureum v.

slope along Sugar Creek
(NCU).

SC 160, east of Fort Mill, 12 Jul 1957, Ahles 31168 with Haesloop

While synonymizing a number of previously named taxa within Eupatorium purpureum L.,
Lamont (1995, 2006) recognized a widespread variety E. purpureum var. purpureum in eastern North
America plus a midwestern variety E. purpureum var. holzingeri (Rydberg) E. Lament. The latter
differs from the typical variety in its "densely puberulent to villous" abaxial sides of leaves (Lamont
1995): it ranges from southern Wisconsin to eastern Nebraska and south to northern Arkansas. Invar.
holzingeri, pubescence occurs on the abaxial leaf blade surface as well as on leaf veins and is
composed of pale translucent-white, lanulose hairs. Pubescence, if any, on abaxial sides of leaves of
var. purpureum is restricted to major veins. Lamont (1995, 2006) stated that "West of the Mississippi
River (and in the high xeric sand-hills of South Carolina), abaxial leaf faces [of var. purpureum] are
commonly densely pubescent along the major veins."

v.ii ..' ■..":;..■:.■.'■:

v.ii : ■.::■:* ' :

'■" .■■■■■■•.■■■■■•■.■■■■■■■

Leaf shape

Broadly ovate to
broadly elliptical, tip
acute to blunt.

Broadly lanceolate to
narrowly ovate, tip
acuminate to acute.

Broadly lanceolate to
narrowly ovate, tip
acuminate to acute.

Leaf margin teeth

Short, acute to bluntish,
not doubly serrate.

1 Lily. vIl.iipK nui.iU

or doubly serrate.

1 Lily. vIl.iipK nui.iU

or doubly serrate.

Leaf abaxial surface

Densely soft lanulose
on surface and veins.

Densely soft lanulose

on surface and veins.

Glabrate, or sparsely
lanulose on veins;
densely lanulose on
veins west of

\||NN|NNipHI klUI

Leaf texture

1 IllJ l^ll. - IIIV^

Thin, not rugose.

Thin, not rugose.

Achene glands at

anthesis

Numerous to abundant,
distinctly long-
papillate.

Sparse to moderate,
very short-papillate.

Sparse to moderate,

very short -papillate.

Lower piedmont of
NC-SC

Midwestern plains

Most of eastern U.S.
ands Ont;

encompasses ranges of
other2vars.

Table 1. Comparison of

Eutrochium purpureum va

r. carolinianum, var. holz

ngeri, and var.

The new variety differs in several ways from Lamont's two varieties (Table 1). Note that var.
carolinianum exhibits significant departures from the norm of E. purpureum in leaf shape, marginal
teeth morphology, and distribution of vestiture on the abaxial surface. The latter condition is matched
only by var. holzingeri, which is disjunct by more man 800 km to the west. These differences give
the new variety a very different gestalt than plants of var. purpureum, which grows sympatrically
with var. carolinianum but is not known to be syntopic with it. Leaf shape and the somewhat thicker
leaf texture are similar to those of E. dubium (Willd. ex Poir.) E. Lamont, but that species' leaves are
much more rugose, the leaves have three main leaf veins, and it inhabits wetlands of the coastal plain,
not dry uplands of the piedmont. Eupatorium steelei (E. Lamont) E. Lamont has similarly shaped
leaves as var. carolinianum, but marginal teeth are sharply serrate, stems are pubescent throughout
(vs. glabrous or glabrate below the inflorescence), and it occurs in the montane region of the Southern
Appalachians.

Sorrie: Eutrochium purpureum v.

The shape and abundance of achene glands of var. carolinianum also exhibit significant
differences from other varieties of Eutrochium purpureum. In the latter, glands are short-papillate or
nearly sessile, and often become difficult to see as the achene matures. In the new variety, the glands
appear to be more numerous, are distinctly longer, and remain easily visible throughout maturation of
the achene.

A small number of specimens show intermediate character states between var, purpureum
and var. carolinianum. These mostly display increased pubescence on leaf abaxial veins and surfaces
as compared with var, purpureum, but none of them are as densely lanulose as in var. carolinianum,
nor do they have long-papillate glands on the achenes. Leaf shape and dentition correspond with var.
purpureum in most specimens. Specimens showing some intermediacy have been seen from
Guilford, Iredell, Macon, and Transylvania counties (North Carolina), McCormick County (South
Carolina), and Montgomery founts (Virginia). Only the McCormick County specimen seems
equivocal in identity. The others are outside of the range of var. carohmanum. as outlined here, and
are identified here as var. purpureum.

Phenology. As with sympatric plants of var. purpureum, plants of the new variety
commence blooming in late June and early July, some three weeks ahead of the two other species of
Eutrochium. in the general region (E. clubium and E. fistulosum (Barratt) E, Lamont).

Habitat. Plants of the new variety inhabit dry oak-hickory woodlands and openings in them
or through them, such as roadsides and powerlines. Canopy species include Quercus alba, Q.
stellata, Carya glabra, C. carolinae-septentrionalis, and Acer rubrum. Understory trees include
Cercis canadensis, Ulmus alata, Acer leucoderme, Cornus florida, anAJuniperus virginiana. The
range of the new variety lies mostly within the Carolina Slate Beit; local soils are usually derived
from mafic metamorphic rocks and are somewhat acidic to circumneutral. Most populations of E.
purpureum var. carolinianum occur in forest openings or clearings, but other populations occur
under a dense canopy. In the latter situation, one would expect co-occurrence with var. purpureum,
but to date the two taxa have not been found growing together (syntopically). This may be an artifact
of limited field work, for var. purpureum also occurs in virtually all of the counties vouchered for var.
carolinianum, as evidenced by historical specimens. In any event, a slight shift in habitat preference
may contribute to lessened genetic contact.

Phytogeography. Despite its reputation for being floristically uninteresting, the lower
Piedmont of the Carolinas (and sometimes extending into adjacent states) features a substantial
number of endemic and disjunct taxa adapted to sunny and open habitats, including Acmispon helleri
(Britt.) Heller, Helianthus laevigatus Torr. & Gray, Helianthus schweinitzii Tost. & Gray, Silphium
terebinthinaceum Jacq,, Solidago plumosa Small, and Solidago radula Nutt. Other endemics and
disjuncts are adapted to more shaded habitats: Carex impressinervia Bryson, Krai, & Manhart,
Euphorbia mercurialina Michx., Eurybia mirabilis (Torr. & Gray) Nesom, and Phacelia covillei S.
Wats, ex Gray. This suite of taxa suggests an interesting biogeographic history of habitats of the
region, which lias generated and maintained a distinctive flora.

ACKNOWLEDGEMENTS

The continued support of the UNC Herbarium and the Flora of Virginia Project is gratefully

acknowledged. I wish to thank curators and managers of NCU and LTSCH for loans of specimens and
access to collections. I thank Guy Nesom for providing the Latin diagnosis.

LITERATURE CITED

Lamont, E.E. 1995. Taxonomy of Eupatorium section Verticillata (Asteraceae). Mem. New York
Bot. Gard. 72: 1-68.

Sorrie; Eutrochium purpureumv.

Lamont, E.E. 2006. Eutrochium. Pages 474-478 in Flora of North America North of Mexico. Vol.
2 1, Magnoliophyta : Asteridae (in part); Asteraceae. Oxford University Press, New York.

Figure 1. Distribution of Eutrochium purpureum var. carolinia
occurs throughout the range of var. carolinianum (see text).

Sorrie: Eutrochium purpureumvar. carolinianum. 5

Figure 2. Holotype oiEutrochium pnrpureum var. carolinianum.

Sorrie: Eutrochium purpureumvar. carolinianum.

_

■

1

Figure 3. Leaves of Eutrochium purpureum var. caroliniam
surface and veins and thickish, rugose texture.

i showing densely soft-lanulose abaxial